Added RAM to iMac 5K 2017, but only running at 2133MHz

[haruhiko]

My iMac came with 16GB of RAM pre-installed and I went to buy 2x8GB Kingston HyperX 2400MHz DDR4 RAM with the package specifically said it supports the iMac 27-inch 2017. However, after installation, the RAM, now totally 32GB (4 x 8GB), only runs at 2133MHz.

I tried to switch the stock RAMs and the Kingston RAMs, but the system won't turn on.

Does anyone know what is wrong with the RAM I bought?
[doublepost=1516360648][/doublepost]The stock RAM is: https://www.micron.com/parts/module...2g3?pc={E1D8F1A9-3DFC-4BD2-8A1E-C26ED261EB0A}
With a CL number of 17

The new RAM is Kingston HyperX which has a CL number of 14.

Guess this is the reason? So there is no way I can make them run at 2400MHz right?

I guess my $200 was wrongly spent...

 

[Samuelsan2001]

My iMac came with 16GB of RAM pre-installed and I went to buy 2x8GB Kingston HyperX 2400MHz DDR4 RAM with the package specifically said it supports the iMac 27-inch 2017. However, after installation, the RAM, now totally 32GB (4 x 8GB), only runs at 2133MHz.

I tried to switch the stock RAMs and the Kingston RAMs, but the system won't turn on.

Does anyone know what is wrong with the RAM I bought?
[doublepost=1516360648][/doublepost]The stock RAM is: https://www.micron.com/parts/modules/ddr4-sdram/mta8atf1g64hz-2g3?pc={E1D8F1A9-3DFC-4BD2-8A1E-C26ED261EB0A}
With a CL number of 17

The new RAM is Kingston HyperX which has a CL number of 14.

Guess this is the reason? So there is no way I can make them run at 2400MHz right?

I guess my $200 was wrongly spent...

Try both sets separately if they run at 2400 when in separately then send the kingston ram back and get some crucial ram that will almost certainly work, use the crucial ram advice page on their website.

 

[haruhiko]

Try both sets separately if they run at 2400 when in separately then send the kingston ram back and get some crucial ram that will almost certainly work, use the crucial ram advice page on their website.

I bought in a retail store.. hopefully I will be able to return them.
I think Kingston or its distributor is very dishonest in marking the RAM 2017 iMac 5K compatible... what a scam!!

 

[nambuccaheadsau]

Just give Kingston a big miss. Crucial and OWC the way to go.

 

[chscag]

Agree. I buy my memory modules either from OWC - Mac Sales (www.macsales.com) or from Crucial. Stay clear of brands that are for PCs or state they're "compatible".

 

[haruhiko]

Finally I found a pair of real 2400MHz (non-Hyper X) RAM (still Kingston as other 8GB 2400MHz SODIMM is out of stock everywhere)

Mac OS finally lists my RAM as running at 2400MHz full speed

For your information this is the correct Kingston RAM to buy:
https://www.kingstonmemoryshop.co.uk/kingston-kcp424ss88-8gb-ddr4-2400mhz-non-ecc-memory-ram-sodimm

Never buy HyperX RAMs.

 

[SaSaSushi]

Never buy HyperX RAMs.

As you read in this thread about RAM for the new iMac (which you also posted to), the HyperX is overlocked which causes problems when it is run together with Apple's stock RAM.

That doesn't mean it's bad RAM nor that it should be avoided. In fact, when installed on its own it performs better than the stock RAM. There are several users in that thread who have removed the Apple RAM and are happily using HyperX alone.

If you are planning to run HyperX together with stock RAM then it is not what you're looking for. If you're replacing the stock RAM then it should be fine.

 

[haruhiko]

Asking for the same money (with a true 2400MHz RAM) for an overclocked RAM which doesn’t play well with other 2400MHz RAMs, with no indication anywhere on the package saying so (the overclocking), is borderline deceptive in my view.

The distributor even added a sticker for “compatibility with iMac 2017 27 inch” on it.

 

[chscag]

Asking for the same money (with a true 2400MHz RAM) for an overclocked RAM which doesn’t play well with other 2400MHz RAMs, with no indication anywhere on the package saying so (the overclocking), is borderline deceptive in my view.

And may in fact void Apple's warranty if something should go wrong with that memory installed. Best to avoid overclocked modules and stick with compatible memory. For those folks who have that memory installed probably know the risks when overclocking memory or the bus.

 

[SaSaSushi]

Asking for the same money (with a true 2400MHz RAM) for an overclocked RAM which doesn’t play well with other 2400MHz RAMs, with no indication anywhere on the package saying so (the overclocking), is borderline deceptive in my view.

I'm not sure that it is the responsibility of Kingston in this case to ensure that its RAM will work together with RAM from other makers.

The distributor even added a sticker for “compatibility with iMac 2017 27 inch” on it.

It is compatible with the 2017 iMac. There are users in these forums happily using it. What it doesn't do is mix well with standard CL17 RAM.
[doublepost=1516498695][/doublepost]

And may in fact void Apple's warranty if something should go wrong with that memory installed. Best to avoid overclocked modules and stick with compatible memory. For those folks who have that memory installed probably know the risks when overclocking memory or the bus.

Perhaps overclocked is an unfair assessment of the Kingston HyperX anyway. It is special, high performance RAM geared towards gamers that is fully tested to run at DDR4-2400. It has a CAS latency of CL14 (the Micron RAM shipped by Apple is CL17) and different timing parameters that lead the iMac to run at 2133MHz when installed together with the stock RAM. When HyperX is used alone, it runs fine at 2400MHz and is actually higher performance.

I am not in here trying to sell the Kingston. I installed 32GB of Crucial Ballistix in addition to the 8GB of Micron my iMac shipped with for 40GB and it's been rock solid. I'm just saying that HyperX is not a bad choice for those that want to use it standalone.

 

[FreemanW]

Asking for the same money (with a true 2400MHz RAM) for an overclocked RAM which doesn’t play well with other 2400MHz RAMs, with no indication anywhere on the package saying so (the overclocking), is borderline deceptive in my view.

The distributor even added a sticker for “compatibility with iMac 2017 27 inch” on it.

As others have alluded to, it is compatible.
However, you paired it up with another manufacturer's product. On a good day, this is a poor idea; and now you have experience on why it is not a good idea to mix brand names of memory.
This scenario sits squarely on the person selecting and installing the memory, no one else.

 

[haruhiko]

Yeah it's always the user's problem. I am ready for these responses at the time when I started the thread. It's MacRumors.

Nevertheless I opened this thread as a reminder to other uninformed iMac users so that they won't repeat my mistake by choosing a RAM that is bad for compatibility.

As far as I can see, many if not most iMac users buy RAM sticks to install with the stock RAM.

Any RAM sticks that are not compatible with the stock RAM must be purchased with caution.

I want to make this very clear to people who would like to add RAM sticks in addition to the stock RAM, DO NOT buy Kingston's Hyper X RAM. You will regret.

 

[SaSaSushi]

I want to make this very clear to people who would like to add RAM sticks in addition to the stock RAM, DO NOT buy Kingston's Hyper X RAM. You will regret.

Yes, this is good advice and it has been reported in these forums by users who tried mixing HyperX with stock RAM as far back as June, 2017 when the new iMac was released.

Again, sorry about your bad experience and especially that you can't get a refund but I'm glad you made the above clarification because the earlier comments you made about Kingston's deceptive labeling and to "never buy HyperX!" were misleading.

For users looking to replace the stock RAM, HyperX is a nice option.

For users looking to add to the stock RAM, I recommend Crucial. Both the "for iMac" DDR4-2400 and Ballistix are excellent choices. Crucial is the consumer division of Micron, manufacturers of the stock RAM that is primarily used in Macs.

 

[FreemanW]

Yeah it's always the user's problem. . . . . .

You're speaking in broad brush generalities when it suits your needs and specifics when casting blame.
The entire point of the posts in this thread that you perceive to be hostile is that the user, when embarking on the Do It Yourself upgrade task, assumes and by definition takes responsibility for orchestrating the harmony of the very parts that user is acquiring and installing.
In this case, you did not do that and as a result, you found out something that you did not previously know.
That is all fine and good.
But you cannot justify laying that dearth of knowledge at the feet of Kingston.